Diol-containing aluminum lubricant

ABSTRACT

A PROCESS FOR LUBRICATING ALUMINUM AND ALUMINUM ALLOYS BY APPLYING TO THE METAL SURFACE A LUBIRCANT COMPRISING A MAJOR PORTION OF A CARRIER FLUID, SUCH AS MINERAL OIL, HYDROCARBON OIL, HALOGENATED OR OXYGENATED HYDROCARBONS, OR WATER, AND A MINOR PORTION OF A C10-C30 A- OR B-DIOL. THE DIOL IS PRESENT AS 0.1-30 VOLUME PERCENT OF THE LUBRICANT.

Dnited States Patent O U.S. Cl. 252-493 11 Claims ABSTRACT OF THE DISCLOSURE A process for lubricating aluminum and aluminum alloys by applying to the metal surface a lubricant comprising a major portion of a carrier fiuid, such as mineral oil, hydrocarbon oil, halogenated or oxygenated hydrocarbons, or water, and a minor portion of a C C aor B-diol. The diol is present as 0.1-30 volume percent of the lubricant.

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of copending application Ser. No. 853,474, filed Aug. 27, 1969, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to the use of diols in the lubrication of the surface of aluminum or aluminum alloys during cold forming processes, machining, including tapping and drilling, or in mechanical devices.

In the rolling of aluminum and aluminum alloys to produce sheet or foil, lubricants are used to decrease friction between the metal and rolls of the rolling mill and to promote good surface finish. These lubricants also serve as heat transfer fluids to remove heat generated in the rolls and metal during rolling.

Lubricants used for rolling of aluminum are almost always mixtures of polar or oiliness additives with a light mineral oil, synthetic hydrocarbon oil, petroleum distillate, or water. The effect of the additives in rolling lubricants is to improve the lubricating ability of the oil or water, thus decreasing friction in the roll bite between rolls and metal. By resultant effects, a decrease in friction allows more efficient reduction in thickness of the metal being rolled. These additives also, through their chemical or polar action, serve to decrease the tendency of the metal to Weld to or pickup on the surface of the rolls during rolling.

Similar lubricants are used to lubricate aluminum parts in engines, gears, and other machinery. Here the problems have been especially acute, and lack of a suitable aluminum lubricant has severely restricted the development of unlined aluminum cylinder engines.

Machining aluminum also requires lubricants. Lack of adequate lubrication during drilling, tapping, or other machining of aluminum seriously shortens the useful life of tools such as drills and taps.

Description of the prior art US. Pats. 2,193,631 and 2,350,570 disclose long-chain monohydric alcohols as components in lubricants. US. Pat. 2,962,401 discloses an aluminum lubricant containing a saturated aliphatic alcohol having less than 8 carbon atoms. US. Pat. 3,124,531 discloses an aluminum lubricant containing polypropylene glycol. .An article by Guminski et al. in I. of the Inst. of Metals, 88, 481 (l959l960) discloses the use of 1,10-decanediol in an npropanol-based aluminum lubricant.

3,649,538 Patented Mar. 14, 1972 ice SUMMARY The process of this invention is a process for lubricating aluminum and aluminum alloys during cold working, machining, or other mechanical operation which comprises applying to the surface of the material a lubricant comprising a major portion of a carrier fluid and a minor portion of a C -C diol having a structure such that the two hydroxy groups are attached to carbon atoms which are either directly bonded together or are separated by one other carbon atom. The carrier tfluid may be a mineral oil, synthetic hydrocarbon oil, petroleum distillate, halogenated or oxygenated hydrocarbon, or water.

DETAILED DESCRIPTION OF THE INVENTION In its broadest form, the process of this invention is a process for lubricating aluminum and aluminum alloys which comprises applying to the surface of the aluminum or aluminum alloy a lubricant comprising a major portion of a carrier fiuid and a minor portion of a C -C diol having a structure such that the two hydroxy groups are attached to carbon atoms which are either directly bonded together or are separated by one other carbon atom. Preferred embodiments will be described below.

The diols used in the process of this invention are C C diols containing any one of the following saturated or aromatically unsaturated structural units:

The generic structure of the diol molecule is OH R OH trait? (l) n represents the number 0 or 1;

(2) R R and when 11:1, R each represents hydrogen or a hydrocarbon group of from 1 to 28 carbon atoms, with at least one being hydrocarbon, and the total number of carbon atoms in the hydrocarbon groups being of from 7 to 28; and

(3) R R and R are each hydrogen or a hydrocarbon group of from 1 to 12, preferably 1 to 6, carbon atoms, or two may be taken together with adjacent carbon atoms to form a carbomonocyclic structure of from 4 to 30, preferably 6 to 30, carbon atoms. The total number of annular carbon atoms in the carbocyclic structure will range from 4 to 8, preferably 5 to 7. and usually 6.

wherein The a-diols are represented by n=0 and the fl-diols by 11:1.

The carbon atoms may be arranged as straightor branched-chain aliphatic, cycloaliphatic, aryl, or ali phatic-substituted aryl configurations. When n is 0, R and R can be joined with the carbon atoms to which they are attached to form a carbocyclic (i.e., alicyclic or aromatic) or substituted carbocyclic structure. Similar- 1y, when n is R and R or R and [R may be taken together with the carbon atoms to which they are attached to form carbocyclic or aliphatic-substituted carbocyclic structures.

Preferred structures include (1) R R and R are as previously defined; and

(2) R R R and R are each hydrogen or a hydrocarbon group of from 1 to 24 carbon atoms, preferably 4 to carbon atoms.

For convenience, structure VI may be referred to as an aliphatic u-diOl, structure VII as an aliphatic fi-diol, structure VIII as a catechol, and structure IX as a mixed alkylaryl diol.

In the lubrication of aluminum, it is important that materials detrimental to the aluminum surface not be present in the lubricant. Consequently, the diols of this invention will contain no atoms other than carbon, hydrogen, and oxygen. Similarly, the carrier fluid should contain no atoms other than carbon, hydrogen, oxygen, and halogen.

The diols useful in this invention are the u-diOlS (11:0) and fi-diols (n=1) such as the 1,2- and l,3-C C alkanediols and the C -C dihydroxy alkylbenzenes. Specific examples include 4 One particular preferred group of diols is the aliphatic terminal diols. These have the formula where R is an aliphatic hydrocarbon group of from 7 to 28 carbon atoms, and the other symbols are as previously defined. Representative of these diols are those wherein R R and R are all hydrogen and which have the formula It is important that there be no more than one carbon atom in the chain between the carbon atom to which one of the hydroxy group is attached and the chain carbon atom to which the second hydroxy group is attached; i.e., that n in the above Formula V be 0 or 1. Since there will be no more than one carbon atom between the points of attachment of the hydroxy groups, the B-diols represent the maximum hydroxy group separation. It has been found that diols having greater hydroxy group separation do not exhibit the superior lubricating properties of the diols of the process of this invention. Rather, the diols having more widely separated hydroxy groups exhibit the properties associated with monohydric alcohols which, as will be shown below, are significantly inferior to the uand fi-diols in the process of this invention.

The diol must contain at least ten carbon atoms and, preferably, at least twelve carbon atoms. It has been found that diols having less than ten carbon atoms do not exhibit the superior anti-wear and lubricating properties of the C -C diols. The lower carbon number diols rather tend to have approximately the same lubricating capacity as the C -C monohydric alcohols. Similarly, diols having more than 30 carbon atoms have not been found to be the equivalent of the C -C diols.

The carrier fluid which comprises the major portion of the lubricant of this invention may be a mineral oil, bydrocarbon oil, hydrocarbon distillate, halogenated or oxygenated hydrocarbon, or water. Water is the preferred carrier fluid because of its high heat removal properties. 'When water is used as the carrier fluid, it is preferred to add a small amount, generally up to about 5-10 volume percent, of an emulsifier to the water/diol mixture. The emulsifier may be ionic or nonionic. Suitable emulsifiers include alkylarylpolyethoxy alcohols, sorbitan monooleate, polyethoxylated amines, amides or fatty acids, sugar esters, soaps, and sulfonates.

Oils suitable as carrier fluids in the process of this invention are generally hydrocarbon oils produced by distillation, cracking, hydrogenation, or other refining processes. They typically have boiling points of 500 to 1,000 P. and viscosities of 50 to 500 SSU at F. A typical example of a suitable oil is a hydrocarbon neutral oil having a viscosity of SSU at 100 F. These may provide a minor amount of lubrication themselves.

Also suitable as carrier fluids are halogenated and oxyginated hydrocarbons. These are particularly preferred as carrier fluids for the a-diols, for the latter often have greater solubility in these non-hydrocarbon fluids than they do in the hydrocarbon fluids.

The oxygenated hydrocarbon fluids useful in this invention include carboxylic acid esters, alcohols, ketones, ethers, and aldehydes. The halogen-substituted hydrocarbons include haloalkyls and haloaryls. The fluids may have both substituents, as in the case of a haloether. Typical non-hydrocarbon fluids which may be used include carbon tetrachloride, 1,1,1-trichloroethane, chloroform, bromoform, 1,2-dichloroethane, chlorobenzene, ethanol, methanol, isopropanol, allyl alcohol, benzyl alcohol, n-butyraldehyde, benzaldehyde, acetone, methyl ethyl ketone, 2-hexanone, methyl isobutyl ketone, ethyl ether, n-propyl ether, ethyl phenyl ether, 1,4-dioxane, and propylene oxide.

The above materials are cited only as examples. Any suitable hydrocarbon, halogenated hydrocarbon, or oxygenated hydrocarbon may be used which can, by the use of suitable emulsifiers, be made miscible with the particular aor fi-diol in question. Further, the carrier fluid may be a mixture of two or more of the above materials. All materials so combined should be mutually miscible or should be capable of being made so by use of appropriate emulsifiers.

In the lubricant composition used in the process of this invention the diol comprises a minor portion. Typically, the diol comprises no more than 30 percent by volume of the diol-carrier fluid mixture. Preferably, the diol is no more than 15 volume percent of the mixture and more preferably, no more than volume percent. The minimum diol concentration is 0.1 volume percent. In a preferred embodiment, the diol is first dispersed in a polyolefin, such as polybutene having a number average molecular weight of about 300- to 1,000. The mixture is then emulsified in water. Such materials are readily volatilized during the annealing of the aluminum following cold rolling, and thus leave little surface residue on the aluminum. Generally, the volumetric ratio of diol to polyolefin is 1:1 to 1:10. In a typical composition of this invention, there will be 90 volume percent water, 2- volume percent diol, 7.5 volume percent polybutene, and 0.5 volume percent nonionic emulsifiers.

The lubricant composition of this invention may also contain conventional additives, such as anti-rust agents, oxidation inhibitors, and lubricity agents. A typical lubricity agent is lard oil. These additives will normally be present as 5-25 weight percent of the lubricant.

Table 1 below illustrates the lubricating properties of the diol lubricants of this invention. The data in this table were derived from a Falex Machine test. This is a well-known test in which a cylindrical shaft of steel is rotated between and in contact with two V-shaped aluminum blocks. The shaft is connected to a motor by a small shear-pin. The shaft and blocks are immersed in the lubricant to be tested. An increasing load is placed on the blocks, forcing them against the shaft. The point at which the shaft seizes against the blocks and shears the shear-pin is measured, and the pounds of force being exerted against the blocks at that point is recorded as the failure load of the lubricant.

In the table below, the aqueous lubricating fluid is of the type described immediately above; 90 percent water, 2 percent diol or comparative test compound, 7.6 percent polybutene (molecular weight of approximately 330) and 0.4 percent commercial nonionic emulsifiers. The nonaqueous lubricating fluid is the 130 SUS neutral oil described above, containing the indicated percentage of diol or comparative test material.

TABLE I Concentra- Falex tion in failure lubricant, lead, Diol vol. percent pounds Aqueous carrier fluid:

1,2-hexadecanediol 2 4, 000 1 ,Z-dcdeeanedioL 2 4, 000 1,2-(C C1!)3lk8n.8di m'urtur 2 3, 050 1,3-alkanediol mixture from 0 -0 olefins. 2 4, 000 Hydrocarbon carrier fluid:

1,2 (C1s-C1g)2lkfll'ldl0l mixture 1 2, 500 1,2-(C15C18)alkanediol mixture 5 2, 800 1.3-alkanediol mixture from C15C1golefins 1 2, 900 1,3-alkanediol mixture from 0 -0 olefins 5 3, 200 2-(l-hydroxyethyl)440 -0 alkyD-G- methylphenol mixture 5 3, 400 2(1"l1ydroxyethyl-4-)1 ,3 ,5 ,7

tetramethyloetyl) phenol 5 2. 750

It is evident from the data of Table I that a wide variety of aand ff-diols are useful in the present invention. Further, the data show that good lubrication is obtained whether the lubricating fluid in which the diols are dispersed is aqueous or non-aqueous.

Table II below illustrates the superiority of the 01- and ,B-diols over similar materials such as diols having wide hydroxy group separation or monohydric alcohols. All materials listed in the following table were present as 2 volume percent of an aqueous lubricant.

TABLE II Falex failure Component: load, pounds l-octadecene 1,7-00 l-octadecanol 1,500 Z-acetoyll-octadecanol 1,500 1,2-diacetoyloctadecane 1,700 1,2-(C -C )alkanediol mixture 3,050 1,3-alkanediol from C -C olefins 4,000 l-hexadecanol 2,350 1,2-hexadecanediol 4,000 l-dodecanol 1,700 1,2-dodecanediol 4,000 1,12-dodecanediol 1,500 3-hydroxymethyl-l-pentadecanol 1,250 3-hydroxyrnethyl- 1 -pentacosanol 1,250

It is apparent from the data of Table II that the aand SB-diols were far superior in their lubricating properties to all the other compounds listed, including closely related compounds such as the diols having more widely separated hydroxy groups and the monohydric alcohols.

The diols used in the process of this invention also have excellent anti-wear characteristics when used as aluminum lubricants. That they are far superior to the corresponding monohydric alcohols in this regard is illustrated below in Table III. The data in Table HI were derived from a modified version of the Falex Machine test described above. In this modification of the test, a constant force was put on the aluminum blocks and the steel shaft rotated between them for a set period of time. At the end of this time, the amount of aluminum worn off the blocks was measured and the milligrams of aluminum lost reported.

It is apparent from the data of Table III that the Otand fi-diols are far superior in their anti-wear properties to related materials.

In a field test, an aluminum; machining lubricant was formulated consisting of weight percent 1,1,1-trichloroethane, 16 Weight percent lard oil, 4 weight percent 1,2- (C C )alkanediol mixture, and a small additional amount of an odorant. This was used in the tapping of aluminum, and was found to increase the tap life more than tenfold over the life (i.e., time to tap breakage) obtained with a lubricant formulated as above but without the diol present.

The diols used in this invention may, in some cases, be obtained commercially, or in other cases may be synthesized. Syntheses of typical aand fl-diols are described below.

EXAMPLE 1 A mixture of 245 g. (1 mole) of Nedox 1518, a commercially available mixture of C C terminal epoxides made from cracked wax olefins and supplied by Ashland Oil and Refining Co., 90 g. moles) of water, and 2 g. of concentrated sulfuric acid catalyst were refluxed for 8 hours at 100 C., washed free of acid, and dried. The product was a waxy white solid, melting point 52 0., containing 1,2-(C -C )alkanediols.

EXAMPLE 2 The procedure described in Example 1 was followed, using 1,2-epoxydodecane as a reactant to produce 1,2- dodecanediol, melting point 53 C.

EXAMPLE 3 The procedure described in Example 1 was followed using 1,2-epoxyhexadecane as a reactant to produce 1,2- hexadecanediol, melting point 49 C.

EXAMPLE 4 A solution containing 270 g. (1 mole) of a mixture of C -C cracked wax olefins, 30 g. (1 mole) paraformaldehyde, 120 g. (2 moles) acetic acid, and 30 g. sulfuric acid catalyst was heated at LOO-120 C. for 24 hours, then washed with dilute NaOH solution and water, to form crude esters. The crude esters were reacted with KOH solution to form a mixture of 1,3(C C )alkanedio1s.

It can be seen from the above discussion that even in quite low concentrations the ocand p-diols are superior aluminum lubricants and anti-wear additives. They have superior load-carrying capacity and the ability to reduce aluminum wear significantly.

I claim:

1. A process for lubricating aluminum and aluminum alloys which comprises applying to the surface of the aluminum or aluminum alloys a lubricant comprising a major portion of a carrier fluid and a minor portion sufiicient to provide lubrication of a C -C diol having a structure in which the two hydroxy groups are attached to carbon atoms which are either directly bonded together or are separated by one other carbon atom and containing only carbon, hydrogen, and oxygen atoms.

2. The process of claim 1, wherein said C -C diol is present as 0.1 to 15 volume percent of said lubrimnt.

3. The process of claim 1, wherein said carrier fluid is water.

4. The process of claim 1, wherein said carrier fluid is a mixture of two or more materials selected from the group consisting of water, mineral oils, hydrocarbon oils, halogenated hydrocarbons, and oxygenated hydrocarbons.

5. The process of claim 1, wherein said carrier fluid is a hydrocarbon oil.

6. The process of claim 1, wherein said carrier fluid is a halogenated or oxygenated hydrocarbon.

7. The process of claim 6, wherein said halogenated hydrocarbon is 1,1,l-trichloroethane.

8. The process of claim 1 wherein said C -C diol has the structural formula (l) n represents the number 0 or 1;

(2) R R and when n=1, R each represents hydrogen or a hydrocarbon group of from 1 to 28 carbon atoms, with at least one being hydrogen, and the total number of carbon atoms in the hydrocarbon groups being of from 7 to 28; and

(3) R R and R are each hydrogen or a hydrocarbon group of from 1 to 12 carbon atoms, or two may be taken together with the carbon atoms to which they are attached to form a carbocyclic structure of from 4 to 30 carbon atoms having of from 4 to 8 annular carbon atoms.

9. The process of claim 8, wherein R R R and R are each hydrogen or a hydrocarbon group of from 1 to 6 carbon atoms.

10. The process of claim 8, wherein said O -C diol is an aliphatic a-diol, an aliphatic ,B-diol,

where R", R R and R are each hydrogen or a hydrocarbon group of from 1 to 24 carbon atoms.

11. An aqueous lubricating composition useful for lubricating aluminum, which comprises:

(a) water;

(b) an aliphatic diol of the formula where R is an aliphatic hydrocarbon group of from 7 to 28 carbon atoms, and n is 0 or 1, said diol being present in said composition in an amount suificient for lubrication; and

(c) an emulsifier in an amount sufiicient to permit the diol to form a stable emulsion with the water.

References Cited UNITED STATES PATENTS 2,267,337 12/1941 Moser et a1 25252 2,606,874 8/1952 Garner et a1 25249'5 X 3,039,969 6/1962 Colueci et a1 25249.5 X 3,043,672 7/1962 Ecke et al 25252 X 3,180,832 4/1965 Furey 25252 X 2,429,905 10/ 1947 Wright 25252 FOREIGN PATENTS 1,065,440 4/1967 Great Britain 25249.5

DANIEL E. WYMAN, Primary Examiner W. H. CANNON, Assistant Examiner U.S. Cl. X.R. 

